DE3525029C2 - Piston-cylinder arrangement - Google Patents

Description

The invention relates to a piston-cylinder arrangement with a cylinders closed at both ends by cylinder covers, one in this axially displaceable piston and one with connected to this, at least one of the cylinder covers urgent piston rod, as well as with a stop arrangement for Stroke limitation.

Such a piston-cylinder arrangement is not in front published published DE 35 02 615 A1, at which consists of fixed stop and counter stop Impact arrangement to limit the adjustment distance between pistons and cylinder serves. There is a signal in this stop arrangement integrated transmitter, which exactly at the moment the Counter-stop at the fixed stop gives a signal. For spe Areas of application has this stop arrangement as proven to be too complex and too expensive, in addition, the can stroke when the piston-cylinder connection is subjected to heavy loads order and high piston speeds adjust what too Malfunctions.  

One has already in DE-OS 26 09 649 an arrangement of proposed here, in which, however, a Adjustment of the stop elements not or only with difficulty and with additional measures that are also possible also complicate the construction and make it more expensive. Similar cher way is also the arrangement according to DE-OS 26 51 398 evaluate.

In contrast, the invention is based on the object above mentioned disadvantages and the piston-cylinder arrangement tion of the type mentioned so that they improve simpler and cheaper construction in all circumstances the practice can be adapted, even with high bean an exact constant of a preset Hu bes is guaranteed.

The above object is achieved according to the invention in a piston-cylinder arrangement solved with the following features:

• a) A closed at both ends with a cylinder cover Cylinder;
• b) a piston which is axially displaceably guided therein;
• c) a piston rod ( 20 ) connected to the piston and penetrating at least one of the cylinder covers;
• d) a stroke arrangement is provided to limit the stroke, which has a fixed stop ( 7 ) attached to the outside of the cylinder and one that cooperates with it, on the part of the piston rod ( 20 ) projecting from the cylinder, which has a counter-stop ( 9 ) surrounding the piston rod ;
• e) the counterstop ( 9 ) is adjustable on the piston rod ( 20 ) in its longitudinal direction and can be releasably fixed in any position;
• f) the piston rod ( 20 ) is provided on its part ( 11 ) protruding from the cylinder ( 10 ) with a threaded section ( 15 ), which is designed as a threaded ring ( 23 ) trained counter stop ( 9 ) in the longitudinal direction of the piston rod ( 20 ) can be screwed back and forth;
• g) on the cylinder penetrated by the piston rod cover is in the direction of the ring nut standing guiding approach forming the fixed stop, which coaxially surrounds the piston rod;
• h) the end face of the counter-stop ( 9 ) designed as a threaded ring ( 23 ), which points towards the guide boss ( 74 ), forms a counter stop face ( 29 ) on the face ( 80 ) of the guide boss ( 74 ) facing it and forming a fixed stop face ( 13 ) can accrue to limit the stroke;
• i) on the fixed stop ( 7 ) is a signal generator ( 48 ) is net, which can be actuated by the counter-stop ( 9 ) in the state on the fixed stop;
• j) on the end face of the threaded ring ( 23 ) having the counter stop surface ( 29 ), a signal transmitter ( 48 ) in the opened state on the fixed stop actuating actuating surface ( 83 ) is provided, which is parallel to the counter stop surface ( 29 ) is ordered and is in particular with this in a common plane;
• k) the signal generator ( 48 ) is set against the fixed stop surface ( 13 ) towards the cylinder ( 10 ) back.

The arrangement according to the invention is characterized by the following Benefits from:

The arrangement according to the invention has a simple and cost Favorable construction, which is exact even under high loads Guaranteed keeping a preset stroke constant. The reduction in the number of components results in also a reduction in castes. Even in the event of a heavy impact of the very narrow counterstop on the festival stop, or in the event of vibrations from other threads no disturbing adjustment of the counter stop. By pre or Screwing the threaded ring back onto the threaded section can the entry for the piston rod into the cylinder varies who the. When the counter-stop hits the fixed stop there is no asymmetrical assembly. The signal generator will be actuated without contact, the adjustment of the sensor surface can be be varied as desired.

Furthermore, it is finally ensured that even with settings the maximum stroke of the threaded section of the piston rod not immersed in the interior of the cylinder and the necessary Seal arranged in the cylinder cover is destroyed.  

Advantageous developments of the piston-Zy according to the invention Linder arrangement are listed in the subclaims.

The invention is explained in more detail with reference to the accompanying drawing tert.

The drawing shows:

Fig. 1 shows a first embodiment of the present invention Kol ben-cylinder arrangement in a side view, wherein the counter-stop is cut,

Fig. 2 shows another embodiment of the piston-cylinder arrangement in side view

Fig. 3 shows a signal generator in section.

In Fig. 1 a first embodiment of the piston-cylinder arrangement according to the invention is shown. You be sitting on both ends closed by cylinder cover Zy cylinder 10 , which is shown for the sake of simplicity in the cut Dar position. Likewise, only a cylinder cover 12 can be seen, which sits on one of the end faces of the cylinder 10 . A piston 14 , shown in dashed lines, is axially displaceably guided in the cylinder and divides the cylinder interior into two working spaces 16 , 18 . On the piston a Kol rod 20 is attached, which penetrates the cylinder cover 12 to the outside. The piston rod 20 can be moved back and forth by optionally pressurizing the two working spaces 16 , 18 in the cylinder 10 .

The following considerations refer to a piston Cylinder arrangement with one-sided out of the cylinder protruding piston rod, however, it should be noted that the invention also applies to a cylinder with a continuous and the  Cylinder can penetrate both ends of the piston rod. The formation of such a piston-cylinder arrangement is then suitably completely symmetrical, the following from In this case, guides refer to both, each other opposite sides of the array.

With reference to FIG. 1 thus is now an end-side region of the Col. ben-cylinder arrangement considered. One can see from the cylinder 10 one of the cylinder covers 12 , to which an axially extending projection 74 is formed and which is arranged concentrically with respect to the cylinder cover 12 . It can have a rectangular shape or, as in the exemplary embodiment according to FIG. 1, a circular outline. Its cross section is reduced compared to that of the cylinder cover 12 . The approach 74 is provided with egg ner centric and coaxial through bore 3 , which is arranged coaxially to the piston rod 20 surrounding through bore 5 of the cylinder cover 12 . The piston rod 20 extends through both bores.

The approach 74 forms a fixed stop 7 on the housing, a rod 20 attached to the part 11 of the piston protruding from the cylinder and fitted with the piston rod 20 , adjustable counter stop 9 . The fixed stop 7 and the counter stop 9 are part of a stop arrangement 1 for limiting the stroke of the piston-cylinder arrangement.

As described, the approach 74 is penetrated by the piston rod 20 with tig, so that its end surface 80 pointing away from the cylinder 10 surrounds the piston rod 20 centrally. At the same time, the end face 80 is arranged in a plane which is oriented transversely to the longitudinal direction of the piston rod 20 . This end face 80 forms the fixed stop surface 13 of the fixed stop 7 , which can cooperate with the counter-stop 9 and is facing this GE.

The counter-stop 9 sits directly on the piston rod 20 and is screwed onto it in an adjustable manner. For this purpose, the piston rod 20 is provided on its portion 11 protruding from the cylinder 10 with a threaded portion 15 which carries the counter stop 9 . The length of the threaded portion is preferably chosen so that the threaded portion 15 at a maximum immersion depth of the piston rod 20 in the cylinder 10 extends only approximately to the transition region between the neck 74 and the cylinder cover 12 . The length of the threaded section 15 thus corresponds at most to the length of the extension 74 . There is a simple reason for this measure:

In the cylinder cover 12 is a not shown and the piston rod 20 against the cylinder cover 12 sealing ring is arranged, which surrounds the piston rod 20 touching. If the threaded section were immersed in this seal, the threads could destroy the sealing ring. This is counteracted by the described design of the threaded section 15 . Of course, this limits the adjustment path of the counterstop 9 , but this is only of secondary importance. The piston-cylinder arrangement described here is primarily intended for applications in which a fine readjustment of the preset stroke is only required from time to time. In areas of application that require both a rough and a fine adjustment of the stroke, a piston-cylinder arrangement is preferably used in the manner of the main patent.

The piston rod 20 is stepped once in the region of its portion protruding from the cylinder and in the region of the threaded section 15 (at 17 ). The gradation 17 separates a batch of the piston rod with a smaller diameter 19 from a batch with a larger diameter 21 . The latter faces the cylinder and carries the threaded portion 15 , the thread approach is formed by the gradation 17 . With this measure, the perfect screwing of the counter-stop 9 onto the piston rod 20 is ensured, first the counter-stop 9 can be pushed over the batch 19 of smaller diameter to the gradation 17 who from where it on the threaded portion 15 of the batch 21 of larger diameter can be screwed on. The difference in diameter is preferably approximately two flank heights of the thread of section 15 .

The counter-stop 9 is of annular shape and formed as a threaded ring 23 , which has a central, coaxial threaded bore 116 . This corresponds in diameter to that of the threaded section 15 , so that the threaded ring 23 can be screwed back and forth on the threaded section 15 in the longitudinal direction of the piston rod 20 . The threaded ring 23 is also designed like a pot and has a U-shaped contour in longitudinal section. The bottom 25 of the cup-shaped ring is flat and extends transversely to the piston rod 20 , being contained in a plane which is at a right angle to the piston rod 20 angeord net.

The bottom 25 of the threaded ring 23 faces towards the fixed stop 7, wherein the recess 27 of the cup-shaped ring nut 23 facing away from the fixed stop. 7 The pointing towards the fixed stop 13 bottom surface of the bottom 25 and the threaded ring 23 forms a counter stop surface 29, which at the emergence of the counter-stop on the fixed stop on its hard-stop surface 13 comes to rest.

By screwing the threaded ring 23 back or forth on the threaded section 15 , the depth of entry of the piston rod 20 into the cylinder 10 can be varied. If the piston-cylinder arrangement is provided with a continuous piston rod and there is also a stop arrangement of the type described on the opposite side of the piston rod, there is the possibility of regulating the stroke of the piston rod both when retracting and when extending, the two Strokes can even be of different lengths.

The threaded ring 23 or counter-stop 9 can be locked in any position on the piston rod 20 , which is preferably done by a clamp. For this purpose, the stop assembly 1 includes a screwed on the threaded portion 15 lock nut 31 which is arranged on the side of the threaded ring 23 remote from the cylinder and in the pot recess 27 is added. By locking the lock nut 31 against the threaded ring 23 , the latter can be set non-rotatably at any point in relation to the piston rod 20 .

It can be seen that both the fixed stop surface 13 and the counter-stop surface 29 each have the shape of a concentrically around the piston rod 20 extending ring surface be sitting, both surfaces are exactly parallel to each other. This has the advantage that when the counter-stop 9 hits the fixed stop 7, no asymmetrical moments are transmitted to the piston rod 20 , which would impose a bending stress on it. Rather, there is a symmetrical transmission of force to the piston rod 20 , it is only subjected to tension or compression, which is practically harmless.

In the stop arrangement described, signal transmitters 48 are integrated, which emit a signal that can be used in terms of circuitry when the respective stop positions between the fixed and counter-stops are reached. The signal transmitters 48 can in particular be electrical, electronic, inductive or pneumatic proximity sensors. Lines for energy supply of the signal generator 48 and for signal acceptance are indicated at 50 . The signal generator 48 are brought to the stop arrangement 1 that they respond exactly when the counter stop 9 hits the fixed stop 7 , ie when the piston-cylinder arrangement approaches an end position of its stroke. The signal obtained can be used, for example, for reversing the pressure medium, but also for other control tasks.

The signal generator 48, which is explained in more detail under FIG. 3, is arranged on the fixed stop 7 . For this purpose, an L-profile 76 is attached to the cylinder cover 12 above the extension 74 , the longer L-leg 78 of which extends parallel to the piston rod and rests on the outer lateral surface 33 of the extension 74 or forms a part with it. The shorter L-leg 79 abuts the axial end face of the cylinder cover 12 and is preferably screwed to the cylinder cover. The longer L-leg 78 ends before reaching the fixed stop surface 13 , ie, its end face 81 is set back relative to the fixed stop surface 13 in the direction of the cylinder 10 . This L-leg carries a signal generator 48 which is only indicated schematically and which can be constructed in the manner of that described under FIG. 3. It is attached to the longer L-leg 78 in the region of the end face 81 and has a sensor surface 56 in the direction of the counter-stop 9 . The sensor surface 9 lies in a plane arranged transversely to the piston rod 20, which is arranged at a parallel, small distance from the plane containing the fixed stop surface 13 .

Just like the fixed stop, the signal generator 48 also works together with the counter stop 9 . To this end (base 25) is blow formed an actuating surface 83 of the counterclaims 9 on the pointing to the signal generator 48 front side to which the signal generator 48 is responsive upon the approach of the counter-stop 9 and emits a corresponding signal. The actuating surface 83 is arranged parallel to the counter abutment surface 29 and, as shown in the exemplary embodiment according to FIG. 1, is preferably arranged together with the same in one plane. So the two surfaces flow into each other. This allows a simple production of the counter-stop 9 , through a single operation, for. B. by facing the threaded ring 23 , both surfaces can be produced simultaneously.

The way it works is as follows:

If the working space 18 of the cylinder 10 adjacent to the extension 74 is acted upon, the piston 14 moves to the left in accordance with FIG. 1 and the piston rod 20 retracts. At the same time the counter-stop 9 moves with, the movement continues until the latter with its counter-stop surface 29 on the fixed stop surface 13 of the fixed stop 7 . Simultaneously at this stroke moment, the contactless actuation of the signal transmitter 48 takes place through the actuating surface 83 , and the signal transmitter transmits a signal which, for example, reverses the direction of movement of the piston by causing a pressure medium supply into the second working space 16 . Since the actuating surface and the counter-stop surface of the counter-stop 9 lie in a common plane, it does not cause any difficulties to precisely adjust the moment of the switching signal output by the switching transmitter 48 to the stop time of the counter-stop on the fixed stop. The distance measured in the longitudinal direction of the piston rod 20 between the fixed stop surface 13 and the reset signal transmitter 48 represents precisely the switching distance which is selected in accordance with the sensitivity of the signal transmitter and can be varied by adjusting the sensor surface 56 (see FIG. 3).

It is understood that the measured with respect to its outer circumference of the threaded ring 23 corresponds at least to the distance of the signal generator 48 from the longitudinal axis of the piston rod 20 . As a result, the highest switching precision is achieved because the actuation surface 83 is arranged exactly axially opposite the signal generator 48 . At the same time, the annular shape of the actuating surface 83 ensures that even if the piston rod 20 is rotated relative to the cylinder 10, the actuating surface is always arranged in an optimal position with respect to the signal transmitter 48 .

It goes without saying that the signal transmitter, for example, can also be inserted directly from the end face 80 into the fixed stop 7 , in which case the outer diameter of the counter-stop could be reduced and the piston-cylinder arrangement is thereby given a more compact appearance. Also white designs are conceivable, also with regard to the counter-stop, which does not necessarily have to have the shape described. However, it is essential in any case that the counter-stop 9 sits indirectly on the piston rod and can be screwed back and forth opposite it. As a result, the counterstop is practically positively fixed in the longitudinal direction of the piston rod, and slipping is also prevented in the event of a strong impact on the fixed stop. The hold of the counter-stop can be supported by the lock nut 31 , which also creates a non-positive connection with the piston rod.

In Fig. 2 another embodiment of the piston-cylinder arrangement is shown schematically, which contains practically the same components as the arrangement of FIG. 1. One recognizes the cylinder cover 12 , the fixed stop 7 , the signal generator 48 , the piston rod 20 and the trained as a threaded ring counter stop 9 . In contrast to the embodiment according to FIG. 1, the counter-stop 9 has the shape of a ring with a square or rectangular cross section, on the end face 35 pointing away from the cylinder 12 a fixing extension 37 is integrally formed, which is designed as a hollow cylindrical sleeve and which has a through-threaded bore 39 which is arranged coaxially to the threaded bore 116 . Both tapped holes have the same diameter. The counter-stop 9 can thus be screwed back and forth together with its fixing extension 37 on the expediently somewhat longer threaded section 15 of the piston rod 20 . In the fixing extension 37 is a Darge presented radial threaded hole is introduced into which a locking screw 43 is immersed, which can be screwed against the threaded portion 15 before. With this locking screw 53 , the counter stop 9 against rotation against the piston rod 20 can be secured ge.

Another exemplary embodiment, not shown, provides that a threaded radial bore is introduced directly into the counter-stop 9 itself and contains a locking screw with which the counter-stop 9 can be screwed in a clamping manner with respect to the piston rod 20 .

The structure of a signal transmitter 48 will be described below with reference to FIG. 3. In this preferred design shown there, a circular-cylindrical, pin-like proximity sensor 52 is used, which has an external thread 54 on its outer jacket. Electrical proximity sensors of this form are commercially available. One of its end faces is designed as a sensor surface 56 , and on its other end face there are line connections 50 for the supply of energy and signaling. The proximity sensor 52 can operate on the principle of inductive damping. In this case, an electromagnetic stray field is imitated on the sensor surface 56 , which is damped when a metal object, the counter-stop, approaches. This attenuation is discriminated and used in a trigger stage to trigger a signal. However, magnetic proximity sensors 52 can also be used, which react to ferromagnetic materials brought into the vicinity of the sensor surface 56 . Last but not least, the use of pneumatic proximity sensors is possible, which imitate an air spray on the sensor surface 56 and detect the pressure increase that results when a body approaches. All these sensors have in common that the sensor surface 56 is relatively sensitive. Direct contact with an emerging body, e.g. B. in the form of a stop should therefore be avoided who. Therefore, the proximity sensor 52 is preferably housed in a protective housing 58, the od a bore 60. Like. At points where the sensor 52 is suitable to be such that is ne sensor surface 56 recessed below the surface 62 of the protective housing 58 comes to lie . Any web-moving masses that are detected by the proximity sensor 52 , that is, the counter-stop, cannot hit the sensor surface 56 directly, but rather they run onto the surface 62 of the protective housing 58 , which at the same time can perform the function of a counter-stop. In the exemplary embodiment according to FIGS. 1 and 2, however, this is excluded, since the signal transmitter is already set back in relation to the fixed stop surface 13 in the opposite direction with respect to the counter stop 9 .

In the case of a proximity sensor 52 with an external thread 54 , the bore 60 of the protective housing 58 is a threaded bore with an internal thread into which the external thread of the proximity sensor 52 fits. The proximity sensor can thus be screwed into the protective housing 58 ; its sensor surface 56 can be adjusted in a simple manner to the desired distance from the surface 62 of the protective housing 58 or the fixed stop surface 13 and there is an advantageous possibility of fixing the proximity sensor 52 in a specific construction position. For this purpose, the other end 64 , at which the line connections 50 are preferably located, protrude from the protective housing 58 , so that a lock nut, not shown, can be screwed onto the protruding threaded section. This then works against the end face 66 of the protective housing 58 .

The protective housing 58 shown in FIG. 3 has the shape of a solid, circular cylindrical sleeve, for. B. made of steel. An external thread 68 is provided on the outer jacket of the sleeve, by means of which the sleeve can be screwed into suitable mounting bores. This form of assembly is simple and versatile. Due to the double thread arrangement on the sleeve - Innenge thread of the bore 60 and external thread 68 - a very precise adjustment of the proximity sensor 52 can be done, for. B. un ter exploiting a differential screw action.

Of course, the protective housing 58 does not necessarily have a circular cylindrical shape, in the game Ausführungsbei of Fig. 1 and 2 it has a cuboid shape and is BEFE with one of its outer surfaces on the L-leg 76 Stigt.

Claims (4)

1. Piston-cylinder arrangement with the following features:

• a) A cylinder closed at both ends by a cylinder cover;
• b) a piston which is axially displaceably guided therein;
• c) a piston rod ( 20 ) connected to the piston and penetrating at least one of the cylinder covers;
• d) a stroke arrangement is provided to limit the stroke, which has a fixed stop ( 7 ) attached to the outside of the cylinder and one that cooperates with it, on the part of the piston rod ( 20 ) projecting from the cylinder, which has a counter-stop ( 9 ) surrounding the piston rod ;
• e) the counterstop ( 9 ) is adjustable on the piston rod ( 20 ) in its longitudinal direction and can be releasably fixed in any position;
• f) the piston rod ( 20 ) is provided on its part ( 11 ) protruding from the cylinder ( 10 ) with a threaded section ( 15 ), which is designed as a threaded ring ( 23 ) trained counter stop ( 9 ) in the longitudinal direction of the piston rod ( 20 ) can be screwed back and forth;
• g) on the cylinder rod penetrated by the piston rod is a in the direction of the threaded ring in front standing, the fixed stop forming guide approach, which comprises the piston rod coaxially;
• h) the end face of the counter-stop ( 9 ) designed as a threaded ring ( 23 ), which points towards the guide boss ( 74 ), forms a counter stop face ( 29 ) on the face ( 80 ) of the guide boss ( 74 ) facing it and forming a fixed stop face ( 13 ) can accrue to limit the stroke;
• i) on the fixed stop ( 7 ) is a signal generator ( 48 ) is net, which can be actuated by the counter-stop ( 9 ) in the state on the fixed stop;
• j) on the end face of the threaded ring ( 23 ) having the counter stop surface ( 29 ), a signal transmitter ( 48 ) in the opened state on the fixed stop actuating actuating surface ( 83 ) is provided, which is parallel to the counter stop surface ( 29 ) is ordered and is in particular with this in a common plane;
• k) the signal generator ( 48 ) is set against the fixed stop surface ( 13 ) towards the cylinder ( 10 ) back.

2. Piston-cylinder arrangement according to claim 1, characterized in that the threaded ring ( 23 ) for its fixing ge compared to the piston rod ( 20 ) by means of a locking screw ( 43 ) can be clamped. 3. Piston-cylinder arrangement according to claim 1, characterized in that the threaded ring ( 23 ) can be fixed by means of a lock nut ( 31 ) which can be screwed onto the threaded section ( 15 ) relative to the piston rod. 4. Piston-cylinder arrangement according to one of claims 1 to 3, characterized in that the length of the threaded section ( 15 ) corresponds at most to the length of the guide projection ( 74 ).